code: def get_ggamma_and_gbeta(self, axis, gamma, gy, x_hat, xp):
      tmp = xp.empty(gamma.size * 2, dtype=gamma.dtype)
      gy.sum(axis=axis, out=tmp[: gamma.size], dtype=gamma.dtype)
      (gy * x_hat).sum(
          axis=axis, out=tmp[gamma.size :], dtype=gamma.dtype
      )
      if xp is cuda.cupy:
          chainer.cuda.Stream.null.synchronize()
      self.comm._multi_node_mean(None, tmp)
      gbeta = tmp[: gamma.size]
      ggamma = tmp[gamma.size :]
      return gbeta, ggamma
  
file_path: chainer/chainermn/functions/batch_normalization.py
imports: import chainer
  from chainer.backends import cuda
  from chainer.functions.normalization import batch_normalization
  import chainer.utils
label_desc: Use image node_id 3 for calling the _MpiImpl obj's underlying member method code with example usage: obj.get_ggamma_and_gbeta(axis, gamma, gy, x_hat, xp) and returns: gbeta,  ggamma